1. Field of the Invention
The invention relates generally to electrical switching apparatus and, more particularly, to electrical switching apparatus, such as circuit breakers. The invention also relates to charging assemblies for electrical switching apparatus. The invention further relates to interlock assemblies for the charging assemblies of electrical switching apparatus.
2. Background Information
Electrical switching apparatus, such as circuit breakers, provide protection for electrical systems from electrical fault conditions such as, for example, current overloads, short circuits, abnormal voltage and other fault conditions. Typically, circuit breakers include an operating mechanism, which opens electrical contact assemblies to interrupt the flow of current through the conductors of an electrical system in response to such fault conditions as detected, for example, by a trip unit. The electrical contact assemblies include stationary electrical contacts and corresponding movable electrical contacts that are separable from the stationary electrical contacts.
Among other components, the operating mechanisms of some low and medium voltage circuit breakers, for example, typically include a pole shaft, a trip actuator assembly, a closing assembly and an opening assembly. The trip actuator assembly responds to the trip unit and actuates the operating mechanism. The closing assembly and the opening assembly may have some common elements, which are structured to move the movable electrical contacts between a first, open position, wherein the movable and stationary electrical contacts are separated, and a second, closed position, wherein the movable and stationary electrical contacts are electrically connected. Specifically, the movable electrical contacts are coupled to the pole shaft. Elements of both the closing assembly and the opening assembly, which are also pivotably coupled to the pole shaft, pivot the pole shaft in order to effectuate the closing and opening of the electrical contacts.
The force required to close the electrical contacts of some low and medium voltage circuit breakers, for example, is greater than what a human can typically provide. For this and other reasons, known closing assemblies typically include at least one stored energy mechanism such as, for example and without limitation, a number of closing springs, to facilitate the closing process. More specifically, the closing spring(s) can be charged either automatically, for example, using an electric motor, or manually, for example, by operating a charging handle that is accessible from the exterior of the circuit breaker housing for this purpose. The charging handle is part of a charging assembly for charging the closing spring(s).
During the manual charging operation, the possibility exists that the charging handle could be unintentionally released (e.g., without limitation, accidently dropped). Under such circumstances, depending on the position of the charging handle, energy that has already been stored (e.g., closing spring(s) partially charged) could be suddenly released, causing damage to one or more components of the closing assembly and/or charging assembly.
There is, therefore, room for improvement in electrical switching apparatus, such as circuit breakers, and in charging assemblies and interlock assemblies therefor.